Assuming that our membership remains at current levels:
Having been in real estate before I have a couple of suggestions. First is that we make sure that we understand the cost of moving, since moving our gear cannot be cheap. Second we should see if our current landlord has a way to accommodate us either at the same property or nearby (if we like our landlord). If we keep the same landlord, generally they will let us move to a larger space without waiting for the lease to run its course. We’d have to sign a new one on the new space, but they’d most likely be willing to waive the rest of the current one. This is pretty common.
While I am extremely against splitting the space (we all benefit by being exposed to people skilled in arts we do not know), it may be possible to find a temporary “annex” space with our landlord while we work out what to do next. We’d make sure the lease on the additional space co-terminus with the current one, and make sure that there is a clause cancelling both leases if we sign a new one for a single larger space at the property. It also behooves us to include a right of first refusal clause on leasing either of the spaces adjacent to the current one. Putting a door through a wall is much cheaper than moving to a new building.
Note that while I know how the game is played I’m not sure that I’m the right guy to negotiate a lease.